SYNOPSIS OF THE BRITISH EPHEMERID^. 19 



dark brown ; wings and venation hyaline, the lon- 

 gitudinal veins of the anterior wings yellowish ; apex 

 of the marginal field with some furcate veins. 

 Female similar to the male, but the abdomen unicolorous 

 brown ; the large egg-valve projects beyond the anus, 

 and is divided by a fissure in half its length into two 

 triangular sharp points. 

 Length of the body $ 4|, 2 5 lines; expansion of the 



wings $ 10, $ lOJ lines; setae $ 11, $ 45 lines. 

 Sub-imago blackish-grey; wings grey, the dark mar- 

 gined veins give them a banded and chequered ap- 

 pearance. In the middle of the anterior wings are 

 a few larger white spots, which arise from the absence 

 in those places of transverse veins. 

 Habitat near London in July, not scarce. 

 This description is made from Prussian specimens which 

 I have compared with the types ; I have English specimens 

 only of the sub-imago. 



Pictet's dimensions are not accurate, especially those given 

 for the caudal filaments. 



? 3. P. DiLUTUS, Stephens ; Eph. diluta, Stephens, 58, 10. 

 The type is wanting; according to the description I ima- 

 gine the species must be a female PotamanthuSj commg near 

 to the preceding in colouring and size ; one can hardly hope 

 to indentify the species with certainty. 



4. P. Fuscus, Stephens ; Eph. fusca, Stephens, 58, 9, 



$ imago ; Curtis, Phil. Mag. 120, 7 ; Eph. rufescens, 



Stephens, 59, 12, ^, 2 imago; Eph. rosea, Stephens, 



59, 13, $ , 2 imago. 



Bactis ohsciircij Stephens ( = Eph. rosea), Qb, 9, 2 imago. 



c2 



